Correctly convert remote port bytecode to uint16 port number. (#321)

* Correctly convert remote port bytecode to uint16 port number.

Copied the network_to_host_short function from the ASIO library to convert the remote port byte code to a uint16 number.

* Switched from uint16_t to unsigned short to work in Windows

* Updated missed uint16_t to unsigned short

ixwebsocket/IXNetSystem.h

@@ -81,4 +81,6 @@ namespace ix
 
     const char* inet_ntop(int af, const void* src, char* dst, socklen_t size);
     int inet_pton(int af, const char* src, void* dst);
+
+    unsigned short network_to_host_short(unsigned short value);
 } // namespace ix